The hermetic compressors of refrigeration systems have their suction usually provided with an acoustic dampening system (acoustic filter or suction muffler), mounted in the interior of the shell and which conducts the gas coming from the suction line to the suction valve.
The suction muffler performs several functions that are important to the good operation of the compressor, such as gas directioning, acoustic dampening and, in some cases, the thermal insulation of the gas being drawn to the interior of the cylinder.
The suction muffler is generally formed by a sequence of volumes and tubes that conduct the gas coming from the suction line directly to the suction valve. This displacement of the gas produces pulses, generating noises which are propagated in a direction opposite to that of the displacement of the gas towards the suction valve. The more efficient the suction muffler in its acoustic outlet through which the gas is admitted, the lower such pulses will be.
Another important function of the suction muffler is to conduct the gas to the suction valve with the lowest possible heating, avoiding thermal exchanges with the gas stagnated inside the shell of the compressor, and also reducing its contact with the hot parts of the interior of the compressor. On the other hand, the suction muffler means load loss for the gas flow being drawn. Its influence on the performance of the compressor is highly important. Most suction mufflers are constructed in a material of low thermal conductivity and affixed to the cylinder head of the compressor through the cylinder cover. The dimensioning of the internal volumes and the length of the tubes of the suction muffler determine, to a great extent, the efficiency thereof.
The suction mufflers generally comprise a hollow base, within which are defined chambers in the form of labyrinths for the passage of gas, and a cover that hermetically closes the hollow base.
There are well known methods for mutually joining and sealing the parts defined by the hollow base and the cover of the suction mufflers, such as through ultrasonic welding, metallic or plastic clamps that promote a sealing with tight fittings, and through adhesives.
The solutions that use welding are not generally satisfactory, since they allow the occurrence of excess welding material in the joining region of the parts of hollow base and cover, which is mainly prejudicial when said excess occurs in the interior of the suction muffler, since it interferes with the gas flow therein and does not guarantee the necessary tightness to the suction muffler.
The solutions using metallic or plastic clamps, as well as those using adhesives or insertion of material between the hollow base and the cover, have as disadvantages the high manufacturing cost and the fact of not guaranteeing the necessary tightness to the suction muffler.
Besides the solutions above, there are also known the solutions for joining the hollow base and the cover, such as those described in documents U.S. Pat. No. 6,394,226 and FR2690376, in which a sealing strap is injected externally to the joining region of said parts, generally involving the external peripheral edge of a pair of peripheral flanges that are mutually seatable, each projecting from the respective part defined by the hollow base and the cover in the joining region thereof. While solving the deficiencies of the techniques mentioned above, such constructions are susceptible to breaks and/or disengagements caused for example by impacts, fatigue or thermal variations, impairing the operation of the compressor.